3
Lighting

Lighting is an essential element of video production. Like the human eye, video cameras need to have an adequate amount of light to produce an acceptable picture. Although today’s video cameras require significantly less light than ever before, the central concern of lighting is not only to provide enough light for the camera to function properly, but also to provide light of a particular quality to achieve the desired aesthetic effect. Whereas the craft of lighting focuses on generating colors and visible detail acceptable to the viewing audience, the art of lighting involves controlling the aesthetic factors that are central to effective productions.

Basic Lighting Concepts

Whether you are producing a program in the studio or in the field, four principal lighting concepts must be considered before you turn on your camera and begin to record. These concepts are baselight, contrast range, color temperature, and light quality.

■ Baselight

The minimum amount of light that is necessary for the camera to function properly is called the base illumination level, or baselight. Each video camera manufacturer provides a measure of the baselight requirements for a camera, also called the operating light level.

• MEASUREMENT OF LIGHT INTENSITY A value for the amount of light required will be given in one of the two basic ways to measure the amount of light: foot-candles or lux. A foot-candle is the amount of light that radiates from a standard candle to a point one foot from the center of the flame. Lux are calculated in the same manner as foot-candles except that the calculation is metric: one meter replaces one foot in the formula.

Foot-candles can be expressed in terms of lumens per square foot. (Lumen is the Latin word for “light.”) Whereas one foot-candle equals one lumen per square foot, one lux equals one lumen per square meter. This results in a ratio of lux to foot-candles of approximately 10:1. That is, ten lux equal approximately one foot-candle; 2,000 lux equal approximately 200 foot-candles.

Most video cameras require about 150–200 foot-candles (or 1,500–2,000 lux) of baselight for optimum operation. This is the amount of light necessary to make a very good picture. A minimum light level may also be specified. This value will be significantly smaller than the optimum baselight level; indeed, for some cameras it may be as low as one or two lux. This is the amount of light necessary to make a visible image. Although you may be able to see the image produced by the camera, the image quality most likely will be quite poor. So don’t be fooled into thinking that this very low light level is the baselight level you should try to achieve. In all situations, your camera will need significantly more light than this to produce a good picture.

• LIGHT METERS Light is measured with a light meter. (See Figure 3.1.) A light meter provides a rough indication of the amount of light entering the camera and expresses the amount in either foot-candles or lux.

Light meters can be used to measure the amount of light falling on a scene, called incident light, or the amount of light reflected off a scene, called reflected light. Incident light is measured by placing the light meter in the subject’s position and pointing it at the source of the light—either a lighting instrument or the sun. A more precise method of measuring the intensity of the light entering the camera involves placing the light meter in the camera position and measuring the light that is reflected from the subject to the camera. This method is more precise because it takes into account differences in the surface reflectance of objects in the scene. A whiteboard will reflect considerably more light back to the camera than will a similar board painted flat black.

Although both types of light meters are widely used in video production, incident light meters are the most common, largely because baselight requirements for cameras are most often reported in terms of the amount of incident light they require.

Some incident light meters have a light-sensitive area that is hemispherical rather than flat. The sphere approximates the shape of the human face and can be used to measure all the light falling on a subject from various directions.

Many video producers avoid using a light meter because the video camera’s viewfinder instantaneously provides an electronic image that the camera operator can observe to judge exposure. And most electronic viewfinders also have built-in exposure meters that indicate the exposure level of the image.

■ Contrast Range

In addition to thinking about the amount of light necessary for the camera to function, some consideration must also be given to the contrast range of the scene before the camera. The contrast range is simply the range between the brightest and darkest parts of a scene. It is typically expressed as a ratio of bright to dark. The human eye is able to process scenes in which the contrast range is 1000:1 and greater; that is, the brightest part of the scene is one thousand times brighter than the darkest. Video cameras, on the other hand, can seldom process scenes in which the contrast range exceeds 100:1.

In practical terms, what this means is that the lighting on a scene should be relatively even. There should not be any extremely bright areas (hot spots) or dark areas. Even if the incident light level is consistent across the scene, differences in the reflectivity of surfaces in the scene can cause contrast range problems. Fortunately, any areas that are too bright or too dark will be immediately apparent in the camera’s viewfinder, so lighting corrections can be made quickly and efficiently.

In field production situations contrast range problems typically arise when a subject to be interviewed is placed against a background that is too bright—a white wall or a window, for example. (See Figure 3.2.) The simple solution to the problem is to move the subject or, in the case of the window, to close the curtains or blinds.

Placing the subject in front of a window often causes the subject to appear in silhouette because of contrast range problems

The issue of contrast ratio or range is further complicated by the capabilities of the recording system and the display system. New developments in high dynamic range (HDR) recording and display systems have significantly increased the contrast range capabilities of recorders and monitors, resulting in images with blacker blacks and whiter whites.

■ Color Temperature

Baselight and contrast range deal with the amount of light and its effect on a scene in terms of its overall brightness. The quality, or color, of that light constitutes the other half of the problem that must be solved to achieve a professional result.

The problem is that what appears to be white light to the eye may not appear to be white to the camera because of differences in the color temperature of the light source. Color temperature is a measure of the relative reddishness or bluishness of light measured in degrees Kelvin (°K).

Differences in color temperature are easily demonstrated by looking at the information in Table 3.1. This table presents a list of common light sources and the color temperature of the light they emit. As you can see from the chart, the flame that is produced by a candle emits light in the range of 1,800°K. The light has a warm, reddish quality to it. At the other end of the scale, outdoor color temperatures may range from 5,600°K to 8,000°K. This light is much cooler and bluer in comparison to the warm flame of the candle.

The problems created by differences in color temperature produced by different light sources are controlled in two ways: by controlling the light sources and by adjusting the camera itself to compensate for different color temperatures.

• CONTROLLING THE LIGHT SOURCE Video studio lighting systems solve the problem of color temperature in a simple way. Studio lighting instruments have traditionally used lamps that emit light at 3,200°K so that color temperature remains constant regardless of camera position or time of day. Because no light is present in a video studio except the light the lighting director puts on the scene, the problem of color temperature is solved. Alternatively, if there is going to be a mix of footage shot outdoors with material shot in the studio, some LED and fluorescent lighting systems can be set to produce light with the daylight color temperature of 5,600°K.

In video field production, the situation is more complex. The color temperature of indoor light produced by household incandescent lamps is different from the color temperature of sunlight. If lighting instruments need to be used to augment the available light, the color temperature of the lighting instruments (which differs both from the color temperature of indoor incandescent lamps and that of outdoor sunlight) must be adjusted to match the existing light. A blue gel can be used to make 3,200°K lighting instruments match the color temperature of daylight (5,600°K, bluish), or a reddish gel can be used to make the 3,200°K instrument a bit warmer to match the color temperature of indoor incandescent light.

• WHITE BALANCE White balance controls on the video camera are used to adjust the camera for the color temperature of the dominant light source. Typical camera settings allow the camera operator to choose from a series of preset positions for different lighting conditions. These may include incandescent, fluorescent, tungsten halogen, and outdoor settings for foggy or overcast or bright sun conditions. Or the white balance may be set manually by focusing the camera on a white card that is illuminated by the dominant light source. In most cases the most accurate white balance is achieved by following the manual white-balancing method.

■ Quality of Light

In addition to the amount and color quality of the light, the overall quality of light, in terms of how soft or hard it is, should be considered. Bright sunlight produces a very hard light, with sharp, distinct shadows on the subject. On the other hand, soft light is produced on an overcast or foggy day; the light is more diffused, and the shadows that are produced are softer and less distinct. (See Figure 3.3.) A variety of lighting instruments have been produced that mimic these qualities of light. These are discussed in more detail later in the chapter.

Lighting Equipment: Types of Lamps

Four principal types of lamps are commonly used in professional video production: tungsten halogen lamps, light emitting diodes (LED), fluorescent lamps, and HMI (halogen metal iodide) lamps. The type of lamp with which you are probably most familiar, household incandescent light bulbs, is not used in professional production applications because they emit light at a color temperature that is a bit too low, and consequently is too red, for use in professional video production.

■ Tungsten Halogen Lamps

Tungsten halogen lamps, also called quartz halogen or quartz lights, were the industry standard for many years and are still found in many professional video lighting instruments. The filament in these lamps is tungsten, and the quartz glass bulb is filled with halogen gas. (See Figure 3.4.) The halogen prevents the tungsten filament from evaporating and coating the inside of the bulb with particles of tungsten that would cause the color temperature of the light to decrease (and become redder) over time. The tungsten halogen lamp maintains a constant color temperature of 3,200°K throughout its life.

Tungsten halogen lamps get extremely hot when they are in use. Care needs to be taken not to place the instruments too close to flammable materials such as curtains in field production applications. In addition, bare fingers must never touch the tungsten halogen lamp; if oil from the skin is deposited on the glass, it may cause the bulb to explode when it gets hot. For this reason, when changing a tungsten halogen lamp, always use cotton gloves or hold the lamp in the foam packing material in which it is shipped.

■ Light Emitting Diodes (LED)

The most recently developed type of lighting instruments used in television and video production utilize light emitting diodes (LED) to create light. Unlike traditional tungsten halogen bulbs, LEDs do not have a filament. In essence they are tiny devices composed of semiconductor material that produce light when an electrical current passes through it. LED instruments for television and video may use hundreds of these tiny LED light bulbs to produce light that is sufficiently bright to illuminate the subject. (See Figure 3.5.)

■ Fluorescent Lamps

Fluorescent lamps provide the standard illumination in the American workplace and in the kitchens and bathrooms of many homes. However, the lamps that are designed for the consumer market do not produce light at a color temperature that is acceptable for video production. Professional fluorescent instruments designed specifically for video production are available with lamps that produce light either at 3,200°K (to match the color temperature of tungsten halogen instruments) or at 5,600°K for use outdoors in daylight. In addition, some manufacturers provide lamps at color temperatures slightly lower than 3,200°K (e.g., 2,900°K and 3,000°K) for use when a warmer lighting effect is desired.

Fluorescent lamps consist of a small or large gas-filled tube. The inside of the tube is coated with a fluorescent material that glows when electrical energy is applied to the gas within the tube.

Fluorescent instruments have become popular in video production in recent years because they consume very little power and generate very little heat in comparison to tungsten halogen instruments. They are very widely used to light newscast sets, and video production facilities that have converted to fluorescent lighting report significant savings over tungsten halogen because of decreased energy and air-conditioning costs.

Although the initial generations of these instruments were large and bulky, today’s units are not. A variety of instruments designed for studio and field are available, as well as extremely small instruments for special lighting situations. (See Figure 3.6.)

Finally, because fluorescent instruments produce an extremely soft, flat light, which is diffused over a large area, they are particularly good for lighting the blue or green screen backgrounds that are used for chroma key effects (which are discussed later in this chapter).

■ HMI Lamps

Hydragyrum Medium Arc-Length Iodide (HMI) lamps produce light that matches the color temperature of daylight. For this reason they are used for daytime outdoor shooting.

These instruments are twice as efficient in terms of foot-candles per watt as tungsten halogen instruments and four times as efficient as tungsten halogen instruments to which filters have been attached to correct their color temperature for daylight. For example, a 2,500-watt HMI unit produces the same amount of light as a 10,000-watt tungsten halogen source with a daylight conversion filter.

Because HMI instruments are often used to add light to large outdoor areas, the instruments themselves tend to be fairly large. In addition, each instrument contains its own ballast, which is used to convert standard 120-volt electrical sources to the direct current the HMI lamps require.

Common Lighting Instruments

Lighting directors have a variety of lighting tools at their disposal. They include a variety of floodlights, spotlights, and soft lights designed for use in the studio and/or in the field.

■ Spotlights and Floodlights

The two basic types of lighting instruments are spotlights and floodlights. Spotlights produce a narrow beam of hard-edged light that produces harsh shadows on the subject; floodlights and soft lights produce a wider beam of softer light that minimizes the presence of shadows on the subject. (See Figure 3.7.)

In recent years there has been a marked trend toward the use of soft lights in video production. Because today’s cameras require less light to operate than their predecessors did, producers do not have to rely on the high-powered spotlights of an earlier era. And because soft lights have a more natural, less artificial look, they are often the right choice for aesthetic reasons as well.

■ Fixed Beam versus Variable Beam Instruments

Lighting instruments may be fixed beam or variable beam. Variable beam lighting instruments allow the lighting director to adjust the beam of light produced by the instrument. On some instruments, the adjustment can be rather significant—varying the beam from floodlight to spotlight, for example. On other instruments, the adjustment may be more minor.

■ Fresnel Spotlight

Fresnel spotlights (see Figure 3.8) contain a lens at the front of the instrument that focuses the beam of light produced by the instrument. Fresnel (pronounced “fruh-nel”) spotlights often include a focusing device, which allows the beam of light to be adjusted from a spotlight (narrow beam) to a floodlight (wider beam).

The Fresnel spotlight is named after Augustin Fresnel, the French inventor of the focusing lens. These lenses were first designed for use in lighthouses in the early nineteenth century. With the use of the Fresnel lens, the light produced by the lighthouse, often fueled by burning whale oil, would be visible as a point of light many miles out to sea.

Fresnel spotlights that are used in studio applications are typically fairly large; 1,000-watt, 2,000-watt, and 5,000-watt instruments are quite common. In small-scale field production situations small 100- to 250-watt Fresnel instruments are popular. Depending on the manufacturer, they may be called Inky or Pepper lights.

■ Parabolic Floodlight

The parabolic floodlight, or scoop (so called because it looks like an old-fashioned ice cream scoop), is an older instrument still used in some video production studios. (See Figure 3.9.) The instrument itself is a parabolic reflector, typically constructed out of brushed metal. Unlike the Fresnel spotlight, it is open-faced; that is, it does not contain a lens.

Parabolic floodlights produce a wide beam of soft, diffuse light. They are used to establish baselight levels in large action areas.

■ Ellipsoidal Spotlight

Ellipsoidal spotlights are used to throw a controlled beam of light over a great distance. (See Figure 3.10.) These instruments contain a Fresnel lens and use an ellipsoid-shaped internal reflector to provide greater control of the light they produce. Ellipsoidal spotlights also contain four internal shutters that can be used to create a variety of light patterns. Ellipsoidal spotlights are frequently used in conjunction with cookies, small metal patterns that are inserted into the instrument to project a pattern (e.g., clouds, trees, and cityscape) onto the background. Sometimes ellipsoidal spotlights are called Lekos or Lekolites, reflecting the brand name given to the ellipsoidal instruments produced by the Century Lighting Company.

■ Fluorescent and/or LED Floodlights

LED and fluorescent floodlights are extremely popular studio lighting instruments because they produce a diffuse light in an instrument with low power consumption and low heat generation. To provide a more focused quality of light that is capable of producing slightly harder shadows and modeling effects, some instruments are equipped with a clear plastic focusing lens. Aluminum or plastic grids or louvers that resemble a honeycomb may also be attached to the front of the fixture to focus the light and reduce the amount of spill light by providing more control over where the light falls. (See Figures 3.5 and 3.6.)

Portable LED and fluorescent instruments are available for field video production as well. However, because the light output of the instruments is rather low, they tend to be used principally to light interview subjects rather than to light large action areas.

■ Soft Lights

Soft lights are widely used in field and studio production settings. They provide a bright light that is even more shadow-free than is the light produced by floodlights. The quality of light produced is particularly flattering for interviews and product demonstrations.

Soft lights that are designed for use in field production typically use a collapsible frame that surrounds the lamp. One type of soft light employs a cloth reflector that is stretched over the frame. The interior of the cloth reflector is covered with an aluminized coating or other reflective material. Another type of soft light system relies on the use of a cloth hood equipped with a front screen composed of diffusion material. The instrument’s light source passes through the layer of diffusion material that softens and diffuses the light. (See Figure 3.11.)

Soft lights for studio applications are considerably larger than field instruments and typically are constructed of metal. The diffusion layer is constructed from rigid translucent plastic that is mounted on the face of the instrument. Increasingly LEDs are used as the lamp of choice in studio and field soft light instruments.

■ Open-Faced Portable Instruments

Lighting instruments that are designed for use primarily in field production settings need to be smaller and lighter than their studio counterparts. Prior to the development of LED instruments, the majority of instruments that were used for small- and medium-scale ENG and EFP applications were open-faced(they have no lens), contained a 500- to 1,000-watt tungsten halogen lamp rated at 3,200°K, and operated on common 110-volt, 60-cycle power. The most common instruments are variable beam spotlights and fixed beam floodlights. (See Figure 3.12.)

Today, small LED lights are replacing tungsten halogen instruments for field production because they are more rugged, use less electrical power, operate at a much cooler temperature, and can easily be switched from 3,200°K to 5,600°K to match the existing ambient light conditions. (See Figure 3.5.)

Light Mounts

■ Field Lights

• FLOOR STANDS Portable lights used in the field are often attached to a telescoping floor stand. The stands are usually made of lightweight aluminum and provide a reasonable amount of stability for the lighting instrument. (See Figure 3.5.)

• CAMERA MOUNTS Camera lights attach directly to the camera and operate on battery power. (See Figure 3.13.) They are widely used in electronic news gathering production activities to provide quick illumination of the reporter or interview subject. Increasingly, camera-mounted lights are equipped with focusing lenses and diffusion filters to produce a softer quality of light.

• HAND-HELD SUPPORTS Some lighting instruments are designed to be hand-held. (See Figure 3.14.) This allows the light to be positioned and moved to fit the needs of the scene and to enhance the modeling of the subject as the subject moves.

■ Studio Lights

One of the advantages of a studio over a field location is that studios are equipped with a smooth floor that makes it easy to move the cameras. To provide a large area with few obstacles to camera movement, studio lights are mounted above the action. (See Figure 3.15.) Some facilities use a fixed pipe grid. Instruments are attached to the grid with C-clamps and a safety chain. Other facilities use moveable light battens, which are counterweighted so that they can be raised and lowered to allow for adjustment without the use of a ladder. Still other facilities use remote-controlled instruments whose position can be adjusted from the control room with the use of a robotic control to pan, tilt, lower, and raise the light. Lights mounted on floor stands may be used as well, particularly when the light source needs to come from below or to the side of the action rather than from above.

Light Modification and Control

A variety of devices are used to provide additional control of the light source.

■ Barn Doors

Barn doors are small metal flaps attached to the top, bottom, and sides of a lighting instrument. (See Figure 3.16.) They are used to control the direction of the light and to keep it from spilling onto unwanted areas of the scene. Barn doors are found more often on spotlights than on floodlights, because spotlights produce more directional light to begin with, which is easier to control than the light produced by a floodlight.

■ Flags

Flags are pieces of opaque material of assorted sizes that are used to keep the light of one instrument from illuminating the wrong part of a set or, as is often the case in field production, to keep sunlight off a subject. Flags may be hand-held, or they may be clamped to a floor stand.

■ Reflectors

Reflectors are used to redirect light back onto a scene. (See Figure 3.17.) Commercial products are available, or they can be made from cardboard or foam core. A plain white card will effectively bounce light back onto the subject, or the card can be covered with aluminum foil. Smooth foil will reflect a hard light; pebble-grained or wrinkled foil will diffuse the light that it reflects and soften the edges of the shadows. If gold foil is available, it will give the reflected light a warmer quality. In field production, lighting umbrellas are often used to soften the light produced by open-faced instruments.

■ Diffusers

Light diffusers, also called scrims, are often used in production to change the amount and quality of light that falls on a scene. (See Figure 3.18.) Professional lighting instruments are fitted with frames or slots to hold the diffusion material. If a frame is not available, a wooden clothespin—also known as a C-47 in professional lighting supply catalogs—can be used to attach diffusion material to the front of a lighting instrument.

Silks are giant diffusers that are used to control light intensity and quality in outdoor productions. They are used like an awning or a tent placed above the scene and situated to filter all the light from the sky.

■ Gels

Gels are plastic or polyester filters, also sometimes called color media. In studio production gels are most often used to change the color of a light source. Gels may be attached to floodlights or spotlights so that they can throw colored light onto a background curtain or wall. In field production gels are most often used to change the color temperature of a light source. When tungsten halogen instruments are used outdoors to augment daylight, blue gels are attached to the front of the lighting instruments to convert their color temperature from 3,200°K to the daylight standard of 5,600°K.

■ Dimmers

Gels, scrims, barn doors, flags, and reflectors give the lighting director a fair amount of control over the direction and quality of the light. However, a more direct control over the amount of light is often needed. Short of adding or subtracting lighting instruments, this is the function of the lighting dimmer. (See Figure 3.19.) Dimmers work by varying the wattage that is supplied to the lighting instrument. If a light is too bright, the wattage can be reduced until the light is at the proper intensity.

Dimmers are used extensively in television studio production as part of a larger lighting control system. Such systems usually include the lighting instruments themselves and a lighting patch panel that works in conjunction with the lighting board. Individual instruments are patched (or connected) to an input on the patch panel that corresponds with a dimmer on the lighting board.

Each lighting instrument may be patched into its own dimmer, or several instruments may be collected together into a group. Lights can be dimmed and brought up in intensity individually, in groups or scenes, or all together. Old-style lighting control systems were operated manually; modern systems are computer controlled. As is the case with many other components of the video production systems, conventional analog dimming units have largely been replaced with digital controllers running on the digital multiplex (DMX) standard.

Portable dimmers are available for field use, but they are seldom used in small-scale productions. Instead, the lighting director might adjust the focus of the light to increase or decrease its intensity, add or subtract diffusion material to make it dimmer or brighter, or move the instrument closer to or farther away from the subject.

Doubling the distance from the lamp to the subject reduces the light that reaches the subject to one-fourth of its original strength. This is the inverse square rule, and it is an important tool in remote video production.

Studio Lighting Principles

■ Base Illumination and Modeling

The video studio provides an environment in which the lighting director (LD) can achieve total control of the lighting design. The reason for this is quite simple: there is no light in the studio except the light that the LD decides to use. In approaching a basic lighting design, two goals will have to be met. First, adequate baselight illumination must be supplied to meet the operational needs of the camera or cameras. Second, the lighting design must be consistent with the production style and desired goals of the program.

Much attention in lighting is focused on meeting the camera’s general baselight requirement. However, the baselight or overall illumination level is only half of the problem; modeling is the other half. Modeling is a lighting effect that is used to create the illusion of three-dimensionality on the subjects that are being illuminated. Baselight, if evenly applied to a scene, often creates a picture that appears to be flat and lifeless. By varying the illumination on the subject—that is, creating a lighting design that includes both highlights and shadows on the subject—a more lifelike three-dimensional lighting effect can be achieved.

■ The Photographic Principle

Lighting to create the illusion of the third dimension involves three tasks: establishing the form of the object (achieved with the use of a key light), reducing the intensity of the shadows created by the key light (this is the function of the fill light or lights), and separating the object from its background (the back light). This technique is known as three-point lighting. (See Figure 3.20.)

• KEY LIGHT The key light is used to establish the form of the object being photographed. It is typically the brightest light on the scene (although sometimes the back light may be brighter, as you will soon see). Because of its brightness, the key light illuminates the object so that it can be seen but also produces shadows on the subject. The position of the light is important: the key light is placed on a line from 30 to 45 degrees above the camera–subject axis and from 30 to 45 degrees to the right or left of that axis. (See Figure 3.21.) A pattern of highlights and shadows created by the key light on the subject’s face that makes the subject appear normal is found somewhere within these angles. Be careful not to position the light too high or low or too far to the center or the side. Your eyes will tell you when you have achieved an aesthetically pleasing effect. (See Figure 3.22.)

• FILL LIGHT The fill light increases the overall light level on a scene and fills in somewhat, but not completely, shadows created on the subject by the key light. (See Figure 3.22.) If you are using a light meter, you might start by adjusting the fill light to one-half to three-fourths of the intensity of the key and then adjust to the desired point by looking at the image as the camera produces it. If the fill light intensity is too high and all or most of the shadows produced by the key are eliminated, the image will appear to flatten out, and the modeling effect will be lost. If the fill light illumination is too low, the fill side of the image may be too dark and/or, depending on the quality of the camera you are using, may exhibit unwanted color or signal artifacts (the colors may seem unnatural, or the picture may appear to be noisy or grainy).

• BACK LIGHT The back light has two functions: it separates the subject from the background by outlining the subject’s head and shoulders with a thin line of bright light; and it supports the modeling effect by revealing facets of the form that are untouched by the key light. The back light is extremely valuable in giving form and highlights to hair or clothing that would otherwise blend into the background. (See Figure 3.22.) The back light is frequently as bright as the key and may be brighter if the subject has dark hair or clothes that disappear into a dark background. The back light should be placed above and behind the subject. However, care must be taken not to position it too high, in which case the subject’s hair and nose may be illuminated out of proportion with the rest of the picture, or too low, in which case the light may radiate directly into the camera lens and produce a distracting lens flare.

• BACKGROUND LIGHT Although traditional three-point lighting does not include the use of a background light, this light can be extremely useful, particularly in interview situations. Background light is different from back light; background light falls on the background of the scene, not on the subject. Often in studio situations an ellipsoidal spotlight with a pattern projector is used to project a pattern onto the background of the scene. This not only provides light, which adds energy and interest to the shot, but also may provide supporting expositional detail if the pattern chosen reinforces the subject of the program.

■ Lighting for Mood and Effect

Although many different techniques for lighting for mood and effect can be described, two basic approaches underscore most lighting designs. Low key lighting and high key lighting refer not to the position of the key light, but to the overall impression of brightness conveyed by the scene. Low key scenes appear to be darker, usually because the background illumination is kept to a minimum. This lighting technique is often used in trying to create the illusion of night in an indoor setting. Such a lighting approach may also suggest an emotional tone that is somber or ominous, depending on the situation. High key scenes are brightly lit. They may convey a sense of brightness, an emotional tone that is upbeat or happy. The lighting design for a murder mystery that is set in an interior location would almost certainly feature low key lighting; a situation comedy staged in the same room would probably utilize high key lighting.

Colored gels on the lighting instruments can also be employed to set the emotional tone of a scene. A futuristic medical experiment might be lit in cool blue tones; a romantic scene in front of a fireplace would probably be enhanced with warm reds.

■ Background Shadows

One of the great challenges of lighting in the studio is to make what is essentially an artificially constructed environment appear to be realistic and natural. Lighting can help to create the illusion, or it can completely destroy it. Nothing is more damaging to maintaining the creative artifice of studio scenes than shadows cast by people in the scene onto the background; this draws attention to the artificiality of the lighting.

To avoid unwanted background shadows, follow these two simple rules: first, make sure that lighting instruments are placed high enough that shadows cast by the people in the scene are relatively short. The higher the key light is positioned, the shorter the cast shadow will be; the lower the key light is positioned, the longer the shadow will be. Second, maintain a reasonable distance (at least six to eight feet) between people in the scene and background curtains or scenery. By doing this, the cast shadows that are created by the key and fill lights will fall onto the floor rather than on the background.

■ Lighting Action Areas

Lighting a scene would be easy if the subjects did not move. Lighting an interview presents a situation in which movement is completely controlled. Lighting a dramatic scene in which actors move about in a set presents another set of challenges. When confronted by a situation in which there will be a lot of movement, you will need to light the overall action area. You may still apply the photographic principle to the problem using multiple lighting instruments for key, fill, and back light functions, although with less precision than you could if your subject were not moving. Overall illumination and separation from the background should be fairly easy to achieve; modeling may be a bit more difficult because of the movement of the characters.

■ Lighting for Chroma Key Backgrounds

Often termed chroma keying (chroma is the Greek word for color), the green screen technique (sometimes blue is used instead of green) has been used in video production since the advent of color.

In a chroma key composited image, the foreground subject is typically recorded in a studio against a blue or green screen background. (See Figure 3.23.) The chroma key background may be either a seamless hard wall or a blue or green cyclorama (curtain). A different background image is recorded separately or, as is the case in the typical news weathercast, is generated via computer. When the two images are combined by using a video switcher (for live production) or in postproduction with image compositing software, the blue or green chroma key background is subtracted from the foreground picture, which is then combined with the new background image.

For the effect to work properly, the blue or green chroma key background must be evenly illuminated and free from shadows. Fluorescent lighting instruments are particularly well suited to this lighting task because they emit an even, soft light at precisely controlled color temperature that can provide relatively shadowless illumination across large background areas.

Any color can be used for a chroma key background, but blue and green are the most popular choices for several reasons. First, they are both primary colors (color television works on a system based on the primary colors of light—red, green, and blue) and therefore can be easily isolated and electronically subtracted from the picture. In addition, there is not much blue in the mix of colors that represent the range of skin tones the camera is likely to see—red is more significantly present. Because people are often featured in the foreground, there is less chance that the face of the on-camera talent will disappear when the chroma key effect is engaged against a blue background. Unfortunately, blue is a popular color for clothing and some performers may have blue eyes. Because green is seldom worn and few people have bright green eyes, a bright shade of green was chosen as an alternative to chroma key blue.

Field Lighting Principles

■ Augmenting Existing Light

As was noted earlier in the chapter, in the studio environment the lighting designer creates a lighting plan from scratch: all of the light on the scene comes from instruments in the studio that have been purposefully selected and placed. In the field, the situation is somewhat different. The challenge is often to control and/or augment existing location light outdoors (from the sun) or indoors (from incandescent or fluorescent fixtures) to achieve the desired lighting effect.

■ Taking Control of Color Temperature

The problem with field locations is that if the location light needs to be augmented with lighting instruments, you have to make sure that your lighting instruments are the same color temperature as the ambient light on the location. The easiest way to do this is to convert the color temperature of the lighting instrument by using an appropriate gel.

Blue gels or dichroic filters (filters that allow only certain frequencies of light to pass through them) can be attached to lighting instruments with tungsten halogen lamps to convert them to the color of average daylight. If you are working with professional fluorescent lighting instruments instead of tungsten halogen, you can replace the 3,200°K professional fluorescent lamps with lamps that are balanced for daylight (5,600°K).

Similarly, LED instruments may be designed to operate either at 3,200°K or 5,600°K. On some instruments, the color temperature setting can be changed with a simple flip of a switch on the instrument itself.

Many videographers find themselves shooting in indoor locations in which a significant amount of illumination is coming from daylight that is entering the scene from a window or skylight. If tungsten halogen instruments need to be used to augment the ambient light in this situation, there are two solutions to the problem of maintaining similar color temperature: blue gels can be applied to the instruments and white balance the camera for daylight, or the color temperature of the daylight can be changed to match the tungsten halogen instruments. This is done by placing amber gels on the windows to convert the color temperature of the daylight coming through them to 3,200°K. But this is not an easy process. The gel must be large enough to cover as much of the window as is visible in the shot, and it must be applied smoothly with no distracting air bubbles or creases that might be visible to the camera. It is almost always easier to gel the lights and/or to close the window shades to block out the offending daylight.

Household fluorescent instruments provide their own set of challenges. Some video cameras have a white balance setting for fluorescent light sources. This is a help, but if daylight is coming in through the windows, you have the same problem described earlier, but with a different set of light sources.

When fluorescent fixtures are present and additional light is being provided by tungsten halogen instruments, the picture will take on a greenish tint if the camera is white balanced for 3,200°K to match the tungsten halogen instruments. If you cannot turn off the fluorescent lights, the next best solution is to obtain some “minus green” gels from a photographic lighting supply store. These gels will filter out light in the green area of the spectrum, making the light from the fluorescent fixtures warmer and suitable for use with the tungsten halogen instruments.

■ Electrical Power Requirements on Location

LED instruments have changed the ballgame when it comes to concerns about the amount of available electrical power needed to power the lights. Most LED instruments use very little power, and several instruments can usually be operated on a single household electrical circuit with little concern about overloading the circuit.

But tungsten halogen instruments are a different story altogether. Because tungsten halogen lighting instruments require a lot of power to operate, the field video producer must consider how many lighting instruments will be used and how much power is available to power them. Generally speaking, two or three portable, open-faced lighting instruments can usually be operated safely on one electrical circuit. (Remember that each circuit may include a number of different electrical outlets.) Usually, all the outlets in one or two adjacent rooms are on the same electrical circuit. To identify the available circuits, find the circuit breaker box. Plug a light into an outlet, and then turn off the circuit breakers one at a time. When the light goes out, you will know which circuit it is on and which circuit breaker controls it. You can then move the light to a different outlet and repeat the process. In this way you will be able to identify all the outlets that are on the same circuit.

You can calculate how much power is available to you by using a simple formula:

watts = amps × volts.

You can determine the number of amps the circuit is rated for by looking at the circuit breaker. The amperage rating will be engraved in the switch. In most houses, circuits of 15 or 20 amps are common. Next, plug the line electrical voltage into the formula, using 120 volts as the standard. So if you have a 20-amp circuit, 20 × 120 = 2,400 watts. If it is a 15-amp circuit, 15 × 120 = 1,800 watts. Next, look at the wattage rating for each of the instruments you are using, and add them up. If you have two 500-watt spotlights and one 1,000-watt floodlight, the total wattage used = 2,000 watts (2 × 500 + 1,000). Your three lighting instruments can be operated safely on the 20-amp circuit, but if the circuit is rated only at 15 amps, your three lights will blow the fuse or trip the circuit breaker because they will exceed the 1,800-watt capacity of the 15-amp line.

■ Lighting an Interview Indoors

One of the most common lighting situations on location is the indoor interview. To light the interview, first assess the light that is available in the room in which you plan to record the interview. Be careful not to position your subject in front of a window; and to avoid background shadows, keep the subject at least six to eight feet away from the back wall.

Figure 3.24 illustrates two typical lighting setups. Figure 3.24a uses standard three-point lighting and assumes that your lighting instruments are providing all of the light on the subject. In Figure 3.24b, the light from the window is used as fill, and the key light and back light are supplied by individual lighting instruments.

■ Outdoor Lighting Problems

The two most common outdoor lighting problems both involve shadows. In shooting on a bright sunny day, the sun will produce harsh shadows on your subject. Besides moving to a different location where the sun is not a factor, two possible solutions to the problem are diffusion and fill light. Just as the light that is produced by a lighting instrument can be softened by the use of diffusion material, so can the sun. Attach a sheet of commercially available diffusion material to a frame made out of plastic pipe. Hold the frame above the subject, allowing the sunlight to pass through it. (Be careful to avoid casting a shadow from the frame on your subject.) The diffusion material will soften the light and create a soft modeling effect on your subject.

An alternative solution to the problem is to use fill light to soften the shadows. A lighting instrument, color corrected for daylight color temperature, will do the trick. Unfortunately, electrical power is often not readily available in outdoor locations. A simpler way to provide the fill light is to use a reflector. A white or silver reflector can be used to reflect a soft or harder light back on the subject, filling in the shadows created by the sun.

The second most common outdoor lighting problem occurs when shadows cast by an object fall on the subject—for example, the shadows of leaves and branches in recording under a tree. This can be a difficult situation to overcome, even with the use of fill lights, diffusers, and reflectors. A better solution is to move the subject either to a place where the subject is completely in the shade or to one where the subject is completely in the sunshine. A reflector or lighting instrument can be used to add some sparkle to a subject that is completely in the shade. If the subject is completely in the sun, you can use one of the techniques described to soften the light and reduce the shadows.

Lighting Safety

A few practical cautions are in order with respect to lighting safety. Lighting safety is the responsibility not only of the lighting director, but also of all of the other members of the production team who will be working around the lights. Consider the following points in lighting in a studio or on location:

1. Dress for success. Setting up and moving lights involve a fair amount of physical activity. Dress properly for this work. Wear sensible shoes (flat-soled, closed-toe) and comfortable pants or shorts. Women should avoid wearing dresses and jewelry.
2. Make sure lights are securely mounted. In the studio, make sure all C-clamps are tightened, and check that safety chains are in place for all instruments. In the field, if possible, place small sandbags on the base of floor stands to give them more stability. Make sure all of the screws that hold the telescoping rods in their extended position are securely fastened. Tape the electrical cord to the floor at the base of the floor stand so that if someone accidentally pulls on the cord, the shock will be absorbed by the tape and the lighting instrument will remain standing.
3. Do not overload electrical circuits. In the studio, know the capacity of each circuit on the dimmer board. In the field, calculate the amount of power your lighting instruments draw and compare that with the amount of power the electrical circuits deliver.
4. Make sure all electrical outlets are properly grounded. This is seldom an issue in the studio, where lighting systems are designed to high standards. In the field, only connect lighting instruments to grounded (three-pronged) outlets. Do not use three-to-two prong adapters to connect three-pronged connectors to ungrounded, two-prong outlets. When electrical equipment is not grounded, it increases the possibility of receiving a serious electrical shock if someone touches the lighting instrument.
5. In the studio, alert other crew members if you are going to raise or lower an instrument.
6. Keep fingers off tungsten halogen lamps. When replacing a burned-out bulb, always use cotton gloves, a piece of soft cloth, or the foam rubber that is supplied with the lamp to shield it from your skin.
7. When using open-faced lighting instruments in the studio or in the field, keep the face of lighting instruments a safe distance away from any flammable surface. These lights get extremely hot. They can easily ignite curtains, and if the folding reflectors on an open-faced floodlight (see Figure 3.11) are not fully open, the instrument may get so hot that the lamp explodes and the instrument melts. This is not good!
8. Wait for lighting instruments to cool down before you move them. Carry insulated electrician’s gloves. If you have to move a hot light in an emergency, insulated gloves will protect you from the instrument’s heat.
9. Water and electricity do not mix. Keep lighting instruments far away from any source of water on the set or on location.

Planning

Clearly, there is a lot to consider in designing and implementing a lighting plan for a studio or remote production. The key to success is thorough planning. Make sure that you have an accurate floor plan of the studio set or remote location. Draw a tentative lighting plot (see Figure 3.25), along with a list of all the lighting equipment you will need. Once your lights are set up and turned on, be sure to look at the image produced by the camera, and be prepared to make adjustments in your lighting setup until you are satisfied with the outcome.